1204.5969 (Hamid Ohadi et al.)

Spontaneous symmetry breaking in a polariton and photon laser    [PDF]

Hamid Ohadi, Elena Kammann, Timothy C. H. Liew, Konstantinos G. Lagoudakis, Alexey V. Kavokin, Pavlos G. Lagoudakis

Here we report on the spontaneous formation of polarisation and coherence in an exciton-polariton condensate in a planar GaAs quantum-well microcavity under pulsed excitation. We have measured the Stokes vector of light emitted by the polariton condensate after each excitation pulse. These single-shot measurements evidenced the build-up of stochastic polarisation with the Stokes vector changing randomly from pulse to pulse. Below threshold the polarisation noise does not exceed 10%, while above threshold we observe a total polarisation of about 50% after each excitation pulse, while the polarisation averaged over the ensemble of pulses remains nearly zero. The stochastic po- larisation build-up is accompanied by the build-up of spatial coherence of the condensate, evidenced by spatial interferometry measurements. The formation of a stochastic spinor order parameter of the condensate is observed both in strong and similarity between polariton and photon lasers.

View original: http://arxiv.org/abs/1204.5969